KR20200137976A - Method for producing modified conjugated diene polymer, modified conjugated diene polymer, polymer composition, crosslinked body and tire - Google Patents

Abstract

The present invention aims to obtain a modified conjugated diene-based polymer having an appropriately high Mooney viscosity, thereby being capable of obtaining a rubber composition with excellent processability, and obtaining a crosslinked body exhibiting excellent low heat generation properties. The modified conjugated diene-based polymer is produced by a method comprising the processes of: obtaining a conjugated diene-based polymer having an active end by polymerizing a monomer including a conjugated diene compound in the presence of a metal amide compound obtained by mixing an alkali metal compound or an alkaline earth metal compound and a compound (A); and making the conjugated diene-based polymer having an active end react with a compound represented by chemical formula (1). (A) is a compound having at least one nitrogen-containing group selected from the group consisting of a protected secondary amino group and a tertiary amino group, and one secondary amino group.

Description

Method for producing a modified conjugated diene polymer, a modified conjugated diene polymer, a polymer composition, a crosslinked product, and a tire TECHNICAL FIELD

The present invention relates to a method for producing a modified conjugated diene polymer, a modified conjugated diene polymer, a polymer composition, a crosslinked product, and a tire.

Conjugated diene-based polymers obtained by polymerization using conjugated diene compounds are excellent in various properties such as heat resistance, abrasion resistance, mechanical strength, and molding processability, and thus various industrial products such as pneumatic tires, anti-vibration rubber, and hoses. Widely used in For example, as a rubber composition used for treads and side walls of pneumatic tires, in order to improve the durability and abrasion resistance of the product, it is preferable to mix a reinforcing agent such as carbon black or silica together with a conjugated diene polymer in the rubber composition. Is known. In addition, in order to increase the affinity between the conjugated diene-based polymer and the reinforcing agent, it is being practiced to prepare a rubber composition using a modified conjugated diene-based polymer modified with a nitrogen-containing compound at one or both ends of the conjugated diene-based polymer. For example, see Patent Document 1 and Patent Document 2).

In Patent Document 1, by reacting a hydrocarbyloxysilane compound having a total of two or more imino groups with a conjugated diene-based polymer having an active end to modify the polymer end, the processability of the polymer composition can be improved, and It is disclosed that a crosslinked rubber excellent in exothermic property can be obtained. In Patent Document 2, a modified conjugated diene-based polymer terminally modified with a hydrocarbyloxysilane compound having one imino group is contained in a specific ratio, and BET and CTAB each contain hydrous silicic acid within a predetermined range. It is disclosed to improve low heat generation property, wet performance, processability, and the like by using a rubber composition. In addition, Patent Documents 1 and 2 describe that the initiation end of the conjugated diene polymer is modified by using a lithium amide compound as a polymerization initiator.

International Publication No. 2017/221943 Japanese Laid-Open Patent Publication No. 2001-131340

As one of the methods for improving the low fuel consumption performance, there is a technique of modifying both ends of a conjugated diene polymer. However, the modified conjugated diene-based polymer in which both ends of the conjugated diene-based polymer are modified has a high Mooney viscosity, and there is a concern that the processability of the rubber composition is deteriorated. In addition, in recent years, due to environmental circumstances and improved consumer awareness of energy savings, as rubber for pneumatic tires, a material having more excellent low fuel efficiency (low heat generation) than before is desired.

The present invention has been made in view of the above problems, a method for producing a modified conjugated diene-based polymer capable of obtaining a rubber composition having an appropriate high Mooney viscosity and good processability, and obtaining a crosslinked product exhibiting excellent low heat generation properties, and The main object is to provide a modified conjugated diene polymer obtained by using the production method.

The present invention provides a method for producing the following modified conjugated diene-based polymer, a modified conjugated diene-based polymer, a polymer composition, a crosslinked product, and a tire.

[1] 　 A step of polymerizing a monomer containing a conjugated diene compound in the presence of a metal amide compound obtained by mixing an alkali metal compound or an alkaline earth metal compound and the following (A) compound to obtain a conjugated diene polymer having an active end And, a step of reacting a conjugated diene-based polymer having the active terminal with a compound represented by the following formula (1), a method for producing a modified conjugated diene-based polymer.

(A) A compound having at least one nitrogen-containing group selected from the group consisting of a protected secondary amino group and a tertiary amino group, and one secondary amino group.

(In formula (1), R ¹ and R ² are each independently a hydrocarbyl group having 1 to 18 carbon atoms, and R ³ is a hydrocarbylene group having 1 to 20 carbon atoms. R ⁴ and R ⁵ are each independently independent of each other. -NR ^a bond between the carbon-hydrogen atom, hydro-car invoke, or hydro-carbon car of invoking a carbon number of 1 to 18 with the at least one of (where, R is ^a hydro-car pray), -N = and -O- It is a monovalent group having 2 to 18 carbon atoms, or R ⁴ and R ⁵ are combined with each other to represent a ring structure formed together with the carbon atom to which they are bonded, provided that R ⁴ and R ⁵ are not hydrogen atoms at the same time. is an integer of 1~3. in this case, n is 1, a plurality of R ¹ in the formula is, it may be the same or different from each other, n is 2 or 3 or when, expression of the plurality of R ² may be the same or different from each other, .)

[2] 　 The modified conjugated diene polymer represented by the following formula (4).

(In formula (4), R ¹ is a C ¹ to C 18 hydrocarbyl group, B ¹ is a C 1 to C 20 hydrocarbyloxy group, or a secondary amino group, a protected secondary amino group and a tertiary amino group A conjugated diene-based polymer chain having at least two nitrogen-containing groups selected from the group consisting of two or more at the terminal R ³ is a hydrocarbylene group having 1 to 20 carbon atoms R ⁴ and R ⁵ are each independently hydrogen bond between the carbon -NR ^a - - atom, hydro car invoke, or hydro-carbon car of invoking a carbon number of 1 to 18 (where, R is ^a hydro-car pray), -N = and the carbon atoms having at least one of the 2 -O- It is a monovalent group of -18, or R ⁴ and R ⁵ are combined with each other to represent a ring structure constituted with the carbon atom to which they are bonded, provided that R ⁴ and R ⁵ do not simultaneously become a hydrogen atom. A conjugated diene-based polymer chain having at least two at the terminal end of at least one nitrogen-containing group selected from the group consisting of a secondary amino group, a protected secondary amino group and a tertiary amino group, n is an integer of 1 to 3. n is 1 In the case of, a plurality of R ^1s in the formula may be the same or different from each other, and when n is 2 or 3, a plurality of B ¹ in the formula may be the same or different from each other.)

[3] A polymer composition comprising a modified conjugated diene polymer obtained by the production method of [1], or a modified conjugated diene polymer of [2], silica, and a crosslinking agent.

[4] A crosslinked product obtained by crosslinking the polymer composition of [3].

[5] A tire in which one or both of a tread and a side wall is formed by using the polymer composition of [3].

According to the present invention, it is possible to obtain a modified conjugated diene-based polymer having an appropriately high Mooney viscosity. By using such a modified conjugated diene-based polymer, a rubber composition having excellent processability can be obtained. Further, according to the present invention, it is possible to obtain a crosslinked rubber excellent in low heat generation properties while making the rubber composition excellent in processability.

(Form for carrying out the invention)

Hereinafter, matters related to the aspect of the present invention will be described in detail. The modified conjugated diene polymer of the present invention is produced by a method including the following polymerization step and modification step.

<polymerization process>

This step is a step of polymerizing a monomer containing a conjugated diene compound to obtain a conjugated diene polymer having an active end. Examples of the conjugated diene compound used in polymerization include 1,3-butadiene, isoprene, 2,3-dimethyl-1,3-butadiene, 1,3-pentadiene, 1,3-hexadiene, and 1,3- Heptadiene, 2-phenyl-1,3-butadiene, 3-methyl-1,3-pentadiene, 2-chloro-1,3-butadiene, and the like. Among these, it is preferable to use at least any one of 1,3-butadiene, isoprene, and 2,3-dimethyl-1,3-butadiene, more preferably containing 1,3-butadiene.

The conjugated diene polymer may be a homopolymer of a conjugated diene compound, but from the viewpoint of increasing the strength of the rubber, it is preferably a copolymer of a conjugated diene compound and an aromatic vinyl compound. As an aromatic vinyl compound used for polymerization, for example, styrene, 2-methylstyrene, 3-methylstyrene, 4-methylstyrene, α-methylstyrene, 2,4-dimethylstyrene, 2,4-diisopropylstyrene, Vinylethylbenzene, divinylbenzene, trivinylbenzene, divinylnaphthalene, t-butoxystyrene, vinylbenzyldimethylamine, (4-vinylbenzyl)dimethylaminoethyl ether, N,N-dimethylaminoethylstyrene, N,N -Dimethylaminomethylstyrene, 2-ethylstyrene, 3-ethylstyrene, 4-ethylstyrene, 2-t-butylstyrene, 3-t-butylstyrene, 4-t-butylstyrene, 5-t-butyl-2- Methylstyrene, vinylxylene, vinylnaphthalene, vinylpyridine, diphenylethylene, diphenylethylene containing tertiary amino groups (e.g., 1-(4-N,N-dimethylaminophenyl)-1-phenylethylene, etc.) Can be mentioned. As the aromatic vinyl compound, it is preferable to use at least one of styrene and α-methylstyrene among these.

When the conjugated diene polymer is a copolymer of a conjugated diene compound and an aromatic vinyl compound, it is preferable that it is a polymer obtained by using 1,3-butadiene and styrene as monomers, especially from the viewpoint of high living property in anionic polymerization. Do. It is preferable that this copolymer has a random copolymerization part in which the distribution of a conjugated diene compound and an aromatic vinyl compound is irregular. Further, the copolymer of the conjugated diene compound and the aromatic vinyl compound may further have a block portion composed of a conjugated diene compound or an aromatic vinyl compound.

When the conjugated diene-based polymer is a copolymer of a conjugated diene compound and an aromatic vinyl compound, the proportion of the aromatic vinyl compound used (that is, the proportion of the structural unit derived from the aromatic vinyl compound in the polymer) is low in the resulting crosslinked polymer. (低) From the viewpoint of improving the balance between hysteresis loss properties and wet skid resistance, it is preferable to set it as 3 to 55% by mass, and 5 to 50% by mass with respect to the total amount of the conjugated diene compound and the aromatic vinyl compound used for polymerization. It is more preferable to set it as %. In addition, the ratio of the structural unit derived from the aromatic vinyl compound in the polymer (hereinafter, also referred to as "bonded styrene content") is a value measured by ¹ H-NMR. As a conjugated diene compound and an aromatic vinyl compound, 1 type may be used individually, respectively, and 2 or more types may be used in combination.

In the above polymerization, as a monomer, a compound different from the conjugated diene compound and the aromatic vinyl compound (hereinafter, also referred to as "other monomer") may be used. As another monomer, acrylonitrile, methyl (meth)acrylate, ethyl (meth)acrylate, etc. are mentioned, for example. The ratio of the other monomers to be used is preferably 10% by mass or less, and more preferably 5% by mass or less with respect to the total amount of the monomers used for polymerization.

As the polymerization method to be used, any of a solution polymerization method, a gas phase polymerization method, and a bulk polymerization method may be used, but a solution polymerization method is particularly preferred. In addition, as the polymerization type, either batch type or continuous type may be used. In the case of using the solution polymerization method, as an example of a specific polymerization method, a method of polymerizing a monomer containing a conjugated diene compound in an organic solvent in the presence of a polymerization initiator and a randomizer used as necessary may be mentioned.

For the polymerization reaction, as a polymerization initiator, an alkali metal compound or an alkaline earth metal compound (hereinafter, also referred to as a ``metal compound''), and at least one nitrogen-containing group selected from the group consisting of a protected secondary amino group and a tertiary amino group It is carried out in the presence of a metal amide compound obtained by using a compound having one secondary amino group (hereinafter, also referred to as "(A) compound") and mixing these metal compounds and (A) compound. By polymerizing the monomer in the presence of the mixture of the metal compound and the compound (A), the nitrogen-containing group derived from the compound (A) can be introduced into the polymerization initiation terminal of the conjugated diene polymer.

As a specific example of a metal compound, for example, methyl lithium, ethyl lithium, n-propyl lithium, n-butyl lithium, sec-butyl lithium, alkyl lithium such as t-butyl lithium, 1,4-dilithobutane, phenyl lithium, Stilbene lithium, naphthyllithium, 1,3-bis(1-litho-1,3-dimethylpentyl)benzene, 1,3-phenylenebis(3-methyl-1-phenylpentylidene)dilithium, Naphthyl sodium, naphthyl potassium, di-n-butyl magnesium, di-n-hexyl magnesium, ethoxy potassium, calcium stearate, etc. are mentioned. Among these, lithium compounds are preferable. The ratio of the metal compounds to be used (when two or more types are used, the total amount thereof) is preferably 0.2 to 20 mmol with respect to 100 g of monomers used for polymerization.

The compound (A) may be a compound having a total of at least one group selected from the group consisting of a protected secondary amino group and a tertiary amino group, and one secondary amino group. In the protected secondary amino group, its protecting group is a functional group which makes the amino group an inert functional group with respect to the polymerization initiator, and is preferably a silyl protecting group. Here, the silyl protecting group is a group in which three hydrogen atoms of ``-SiH ₃ '' are each substituted with a hydrocarbyl group, and specific examples thereof include, for example, trimethylsilyl group, triethylsilyl group, tert-butyldimethylsilyl group, Triisopropylsilyl group and tert-butyldiphenylsilyl group are mentioned. Since the dispersibility of silica can be sufficiently high and an excellent modified conjugated diene polymer can be obtained by low heat generation, the compound (A) is a compound having a protected secondary amino group and one secondary amino group. It is desirable.

The compound (A) may be any of a chain compound and a cyclic compound, but is preferably a cyclic compound, and more preferably a heterocyclic amine. The (A) compound is particularly preferably at least one type selected from the group consisting of a compound represented by the following formula (2) and a compound represented by the following formula (3).

(In formula (2) and formula (3), A ¹ , A ² and A ³ are each independently a silyl protecting group or a hydrocarbyl group. R ⁶ , R ⁷ , R ⁸ , R ⁹ and R ¹⁰ are, Each independently is a hydrocarbylene group.)

For A ¹ , A ² and A ³ in the above formulas (2) and (3), examples of the hydrocarbyl group include a linear or branched alkyl group, an aryl group, and an aralkyl group. The number of carbon atoms in the hydrocarbyl group is preferably 1 to 20, more preferably 3 to 10.

It is preferable that A ¹ , A ² and A ³ are silyl protecting groups from the viewpoint of being able to improve the rolling resistance (low heat generation) of the resulting vulcanized rubber.

The hydrocarbylene group of R ⁶ to R ¹⁰ is preferably a linear or branched alkanediyl group. The number of carbon atoms in the hydrocarbylene group is preferably 1 to 10, more preferably 1 to 3.

As a specific example of the compound (A), a compound represented by each of the following formulas (a-1) to (a-9) is exemplified.

In addition, when polymerization is carried out in the presence of a metal amide compound obtained by mixing a metal compound and a compound (A), the metal compound and the compound (A) are mixed in advance, and the mixture thereof may be added to the polymerization system to perform polymerization. . Alternatively, the metal compound and the (A) compound may be added separately or simultaneously in the polymerization system, and both may be mixed in the polymerization system to perform polymerization. In either case, it is included in the aspect of "polymerizing a monomer containing a conjugated diene compound in the presence of a metal amide compound obtained by mixing an alkali metal compound or an alkaline earth metal compound and the compound (A)."

The amount of the compound (A) to the metal compound can be appropriately set according to the type of the metal compound to be used. For example, when metallic lithium is used as the metal compound, the amount of the compound (A) is preferably in the range of 0.1 to 1.8 moles with respect to the total 1 mole of metallic lithium used in the polymerization. From the viewpoint of suppressing the decrease in processability when the rubber composition is used, the amount of the compound (A) is preferably less than 1 mol, more preferably 0.98 mol or less, with respect to 1 mol of the total amount of metal lithium used for polymerization. And more preferably 0.95 mol or less. In addition, from the viewpoint of sufficiently obtaining the effect of improving the low fuel consumption performance, the amount of the compound (A) is preferably 0.2 mol or more, and more preferably 0.3 mol or more with respect to the total 1 mol of metallic lithium used in the polymerization. In addition, as the compound (A), it can be used alone or in combination of two or more.

The randomizer can be used for the purpose of adjusting the content of vinyl bonds indicating the content of vinyl bonds in the polymer. Examples of randomizers include dimethoxybenzene, tetrahydrofuran, dimethoxyethane, diethylene glycol dibutyl ether, diethylene glycol dimethyl ether, 2,2-di(tetrahydrofuryl)propane, and 2-(2-ethoxye). Oxy)-2-methylpropane, triethylamine, pyridine, N-methylmorpholine, tetramethylethylenediamine, and the like. As a randomizer, these 1 type can be used individually or in combination of 2 or more types.

As the organic solvent used for polymerization, any organic solvent inert to the reaction may be used. For example, aliphatic hydrocarbons, alicyclic hydrocarbons, aromatic hydrocarbons, and the like can be used. Among them, hydrocarbons having 3 to 8 carbon atoms are preferred. Specific examples of the organic solvent used for polymerization include, for example, propane, n-butane, isobutane, n-pentane, isopentane, n-hexane, cyclohexane, propene, 1-butene, isobutene, trans-2- Butene, cis-2-butene, 1-pentine, 2-pentene, 1-hexene, 2-hexene, benzene, toluene, xylene, ethylbenzene, heptane, cyclopentane, methylcyclopentane, methylcyclohexane, 1-pentene , 2-pentene, cyclohexene, and the like. Moreover, as an organic solvent, 1 type can be used individually or 2 or more types can be combined and used.

In the case of solution polymerization, the monomer concentration in the reaction solvent is preferably 5 to 50% by mass, more preferably 10 to 30% by mass, from the viewpoint of maintaining a balance between productivity and ease of polymerization control. It is preferable that it is -20 to 150 degreeC, and, as for the temperature of a polymerization reaction, it is more preferable that it is 0 to 120 degreeC. Further, the polymerization reaction is preferably carried out under a pressure sufficient to keep the monomer in a substantially liquid state. Such a pressure can be obtained by a method such as pressurizing the inside of the reactor with a gas that is inert to the polymerization reaction.

By such a polymerization reaction, a nitrogen-containing group derived from the compound (A) is introduced at one end, and a conjugated diene polymer having an active end at the other end can be obtained. The weight average molecular weight (Mw) in terms of polystyrene by gel permeation chromatography (GPC) of the obtained conjugated diene polymer is preferably 5.0×10 ^{4 to} 1.0×10 ⁶ . When Mw is less than 5.0×10 ⁴ , the tensile strength, low heat generation and abrasion resistance of the crosslinked polymer tend to be deteriorated, and when it is larger than 1.0×10 ⁶ , the processability of the rubber composition obtained using the modified polymer tends to decrease. There is a tendency. Mw is more preferably 8.0×10 ⁴ or more, and still more preferably 1.0×10 ⁵ or more. Further, Mw is more preferably 8.0×10 ⁵ or less, and still more preferably 5.0×10 ⁵ or less.

With respect to the conjugated diene-based polymer having an active end, the vinyl bond content in the butadiene unit is preferably 30 to 70% by mass, more preferably 33 to 68% by mass, and furthermore 35 to 65% by mass. desirable. When the vinyl bond content is less than 30 mol%, the grip property tends to be low, and when it exceeds 70 mass%, the abrasion resistance of the obtained vulcanized rubber tends to decrease. In addition, in the present specification, the ``vinyl bond content'' is a value representing the content ratio of the structural unit having 1,2-bonds to all the structural units of butadiene in the conjugated diene polymer, and ¹ H-NMR It is a value measured by.

<Denature process>

In this step, the active terminal of the conjugated diene-based polymer obtained in the polymerization step is reacted with a compound represented by the following formula (1) (hereinafter, also referred to as "(M) compound"). Accordingly, a modified conjugated diene-based polymer in which a group (secondary amino group) interacting with silica is introduced at the end of polymerization can be obtained.

(In formula (1), R ¹ and R ² are each independently a hydrocarbyl group having 1 to 18 carbon atoms, and R ³ is a hydrocarbylene group having 1 to 20 carbon atoms. R ⁴ and R ⁵ are each independently independent of each other. -NR ^a bond between the carbon-hydrogen atom, hydro-car invoke, or hydro-carbon car of invoking a carbon number of 1 to 18 with the at least one of (where, R is ^a hydro-car pray), -N = and -O- It is a monovalent group having 2 to 18 carbon atoms, or R ⁴ and R ⁵ are combined with each other to represent a ring structure formed together with the carbon atom to which they are bonded, provided that R ⁴ and R ⁵ are not hydrogen atoms at the same time. is an integer of 1~3. in this case, n is 1, a plurality of R ¹ in the formula is, it may be the same or different from each other, n is 2 or 3 or when, expression of the plurality of R ² may be the same or different from each other, .)

In the formula (1), the hydrocarbyl group of R ¹ and R ² includes, for example, an alkyl group having 1 to 18 carbon atoms, an allyl group, a cycloalkyl group having 3 to 18 carbon atoms, and an aryl group having 6 to 18 carbon atoms. . Examples of the hydrocarbylene group for R ³ include an alkanediyl group having 1 to 20 carbon atoms, a cycloalkylene group having 3 to 20 carbon atoms, and an allylene group having 6 to 20 carbon atoms. R ³ is preferably a linear or branched alkanediyl group having 1 to 20 carbon atoms, and more preferably a linear alkanediyl group having 2 to 15 carbon atoms.

The hydrocarbyl group of R ⁴ and R ⁵ is, for example, a straight-chain or branched alkyl group having 1 to 18 carbon atoms, an allyl group, a cycloalkyl group having 3 to 18 carbon atoms, an aryl group having 6 to 18 carbon atoms, and Aralkyl groups are mentioned.

When at least one of R ⁴ and R ⁵ is ^a monovalent group having 2 to 18 carbon atoms having at least any of -NR ^a -, -N= and -O- between the carbon-carbon bonds of the hydrocarbyl group, as a specific example thereof, A group having -NR ^a -, -N= or -O- between carbon-carbon bonds of an alkyl group having 2 to 18 carbon atoms; A group in which one hydrogen atom has been removed from the ring portion of a saturated or unsaturated monocyclic or condensed ring such as pyridine, pyrimidine, pyrazine, quinoline, oxane, furan, and pyran. R ^a is preferably an alkyl group having 1 to 5 carbon atoms.

Specific examples of the ring structure in which R ⁴ and R ⁵ are joined together with the carbon atom to which they are bonded include a cycloalkylidene group having 3 to 18 carbon atoms, a heterocyclic group having at least one of a nitrogen atom and an oxygen atom in the ring portion, etc. Can be lifted.

Since n can make the improvement effect of silica dispersibility higher, 2 or 3 is preferable and 3 is more preferable.

As a specific example of the (M) compound, for example, a compound represented by each of the following formulas (m-1) to (m-8), and an alkyl group and an alkanediyl group in the following compounds are each an alkyl group having 1 to 6 carbon atoms, And compounds substituted with an alkanediyl group having 1 to 6 carbon atoms. In addition, as the compound (M), one type may be used alone, or two or more types may be used in combination.

The reaction between the conjugated diene-based polymer having an active terminal and the compound (M) can be, for example, a solution reaction. The ratio of the (M) compound to be used (in the case of using two or more types, the total amount thereof) is 0.01 mol or more with respect to 1 mol of metal atoms involved in polymerization of the polymerization initiator from the viewpoint of sufficiently advancing the denaturation reaction. It is preferable and it is more preferable to set it as 0.05 mol or more. In addition, in order to avoid excessive addition of the (M) compound, the ratio of the (M) compound to be used is preferably less than 2.0 moles, and less than 1.5 moles per 1 mole of the metal atoms involved in the polymerization of the polymerization initiator. It is more preferable to do it.

The temperature of the denaturation reaction is usually the same as that of the polymerization reaction, preferably -20°C to 150°C, more preferably 0 to 120°C. When the reaction temperature is low, the viscosity of the polymer after modification tends to increase, and when the reaction temperature is high, the polymerization active terminal is easily deactivated. The reaction time is preferably 1 minute to 5 hours, more preferably 2 minutes to 1 hour.

In the reaction of the conjugated diene-based polymer having an active terminal with the (M) compound, a modifier different from the (M) compound (hereinafter, also referred to as ``other modifiers'') or a coupling agent may be used together with the (M) compound. Also good. The other modifier or coupling agent is not particularly limited as long as it is a compound capable of reacting with the active end of the conjugated diene polymer obtained by the polymerization, and a known compound can be used as the modifier or coupling agent of the conjugated diene polymer. When other modifiers or coupling agents are used, the ratio of use thereof is preferably 10 mol% or less with respect to the total amount of the modifier and coupling agent used in the denaturation reaction of the conjugated diene polymer having an active end, It is more preferable to set it as 5 mol% or less.

In order to isolate the modified conjugated diene polymer contained in the reaction solution, for example, it can be carried out by a known solvent removal method such as steam stripping and drying operations such as heat treatment. The modified conjugated diene-based polymer thus obtained has a structure in which a conjugated diene-based polymer chain is bonded to the reaction point (carbon-nitrogen double bond (C=N group), alkoxysilyl group) of the compound (M). Further, it is considered that the C=N group is more reactive than the alkoxysilyl group and reacts preferentially with the active terminal of the conjugated diene polymer.

The modified conjugated diene polymer obtained by the polymerization step and the modification step is represented by the following formula (4).

(In formula (4), R ¹ is a C ¹ to C 18 hydrocarbyl group, B ¹ is a C 1 to C 20 hydrocarbyloxy group, or a secondary amino group, a protected secondary amino group and a tertiary amino group A conjugated diene-based polymer chain having at least two nitrogen-containing groups selected from the group consisting of two or more at the terminal R ³ is a hydrocarbylene group having 1 to 20 carbon atoms R ⁴ and R ⁵ are each independently hydrogen bond between the carbon -NR ^a - - atom, hydro car invoke, or hydro-carbon car of invoking a carbon number of 1 to 18 (where, R is ^a hydro-car pray), -N = and the carbon atoms having at least one of the 2 -O- It is a monovalent group of -18, or R ⁴ and R ⁵ are combined with each other to represent a ring structure constituted with the carbon atom to which they are bonded, provided that R ⁴ and R ⁵ do not simultaneously become a hydrogen atom. A conjugated diene-based polymer chain having at least two at the terminal end of at least one nitrogen-containing group selected from the group consisting of a secondary amino group, a protected secondary amino group and a tertiary amino group, n is an integer of 1 to 3. n is 1 In the case of, a plurality of R ^1s in the formula may be the same or different from each other, and when n is 2 or 3, a plurality of B ¹ in the formula may be the same or different from each other.)

In the above formula (4), the description of the above formula (1) applies to R ¹ , R ³ , R ⁴ and R ⁵ . For B ¹ , the hydrocarbyloxy group is preferably an ethoxy group or a methoxy group. The conjugated diene-based polymer chain of B ¹ and Poly in the formula (4) are the conjugated diene-based polymer obtained by the polymerization reaction in the polymerization step, that is, a nitrogen-containing group derived from the compound (A) at one end. It is a structure corresponding to a conjugated diene-based polymer introduced and having an active end at the other end.

<Polymer composition>

The polymer composition of the present invention contains a modified conjugated diene polymer (hereinafter also referred to as "specific modified conjugated diene polymer") modified using the compound (A) and the compound (M), silica and a crosslinking agent. The content of the specific modified conjugated diene polymer in the polymer composition is preferably 10% by mass or more, more preferably 20% by mass or more, and even more preferably 25% by mass or more with respect to the total amount of the polymer composition. In addition, the content of the specific modified conjugated diene-based polymer in the polymer composition is preferably 50% by mass or less, and more preferably 40% by mass or less with respect to the total amount of the polymer composition.

Examples of the silica include wet silica (hydrous silicic acid), dry silica (silicic anhydride), colloidal silica, precipitated silica, calcium silicate, and aluminum silicate. Among these, wet silica is particularly preferred from the viewpoint of an effect of improving fracture properties and an effect of both wet grip resistance and low rolling resistance. Further, the use of highly dispersible type silica is also preferable from the viewpoint of improving physical properties and processability while improving dispersibility in the polymer composition. In addition, silica can be used alone or in combination of two or more.

In addition to silica as a filler, the polymer composition may contain various reinforcing fillers such as carbon black, clay, and calcium carbonate. Preferably, it is silica alone or a combination of carbon black and silica. The total amount of silica and carbon black in the polymer composition is preferably 20 to 130 parts by mass, more preferably 25 to 110 parts by mass, based on 100 parts by mass of the total amount of the polymer component contained in the polymer composition.

Examples of the crosslinking agent include sulfur, halogenated sulfur, organic peroxides, quinone dioximes, organic polyvalent amine compounds, and alkylphenol resins having a methylol group, and sulfur is usually used. The blending amount of sulfur is preferably 0.1 to 5 parts by mass, more preferably 0.5 to 3 parts by mass, based on 100 parts by mass of the total amount of the polymer components contained in the polymer composition.

In the polymer composition, as a rubber component, in addition to the specific modified conjugated diene-based polymer, a rubber component different from the specific modified conjugated diene-based polymer (hereinafter referred to as "other rubber components") may be blended. The type of the other rubber component is not particularly limited, but a butadiene rubber (for example, a cis-1,4-linked 90% or more high cis BR, syndiotactic-1,2-polybutadiene (SPB)-containing BR, etc.), Styrene butadiene rubber (SBR), natural rubber (NR), isoprene rubber (IR), styrene isoprene copolymer rubber, butadiene isoprene copolymer rubber, and the like may be mentioned. Other rubber components are more preferably BR and SBR. The content of the other rubber components in the polymer composition is preferably 60% by mass or less, and more preferably 50% by mass or less with respect to the total amount of the specific modified conjugated diene-based polymer and other rubber components.

In the polymer composition, a process oil generally used for oiling an elastomer may be blended as an oil for oil field. The process oil is formulated into the polymer composition, for example by adding the oil directly during rubber compounding. Preferred process oils include various oils known in the art, for example, aromatic oils, paraffinic oils, naphthenic oils, vegetable oils, and oils with a low content of polycyclic aromatic compounds (low PCA Oil), for example mild extraction solvate (MES), treated distillate aromatic extract (TDAE), special aromatic extract from residual oil (SRAE) residual aromatic extract) and heavy naphthenic oil. Examples of commercially available MES, TDAE and SRAE include Catenex SNR manufactured by Shell (heavy paraffin dewaxed from spilled oil as a solvent) as MES, Vivatec 500 manufactured by H&R Wasag AG as TDAE, and Japan Energy Corp. Manufacturing NC140, etc. are mentioned. The blending amount of the process oil is preferably 10 to 100 parts by mass with respect to 100 parts by mass of the total amount of the polymer components contained in the polymer composition.

In addition to the above components, the polymer composition includes, for example, an anti-aging agent, zinc oxide, stearic acid, softener, sulfur, vulcanization accelerator, silane coupling agent, compatibilizer, vulcanization aid, processing aid, scorch inhibitor, etc., rubber for tires. Various additives generally used in the composition can be blended. The blending amount of these can be appropriately selected according to various components within a range that does not impair the effects of the present invention.

In addition to the rubber component, silica, and crosslinking agent, the polymer composition is kneaded using a kneader such as an open kneader (e.g., roll) or a closed kneader (e.g. Banbury mixer). And, by crosslinking (vulcanization) after molding, it can be applied to various rubber products as a crosslinked product. Specifically, the crosslinked product may be used in tire applications such as tire tread, under tread, carcass, side wall, and bead portion, for example; Sealing materials such as packing, gasket, weather strip, and O-ring; Interior and exterior skin materials for various vehicles such as automobiles, ships, aircraft, and railways; Building material; Anti-vibration rubbers for industrial machinery and equipment; Various hoses and hose covers such as diaphragm, roll, radiator hose and air hose; Belts such as power transmission belts; Lining; Dust boots; Medical device material; Fender; Insulating materials for electric wires; It can be applied to other uses such as industrial products.

According to the production method of the modified conjugated diene-based polymer of the present invention, a modified conjugated diene-based polymer having high Mooney viscosity, good shape stability, and excellent processability when used as a rubber composition, has low heat generation properties and wet grip resistance. In the same way, it can be obtained while maintaining good properties required for tire applications. Therefore, the rubber composition containing the modified conjugated diene-based polymer obtained by the production method is particularly suitable as a material for one or both of a tread and a side wall of a tire.

Manufacturing of a tire can be performed according to a commercial method. For example, a polymer composition is mixed with a kneader, and a sheet-like product is placed in a predetermined position (for example, the outside of the carcass in the case of a side wall) and vulcanized and molded according to a conventional method. Formed as rubber, a pneumatic tire is obtained.

(Example)

Hereinafter, although it demonstrates concretely based on an Example, this invention is not limited to these Examples. In addition, "part" and "%" in Examples and Comparative Examples are based on mass unless otherwise noted. The measuring method of various physical property values is shown below.

[Evaluation of polymer properties]

-Vinyl content (%): measured by ¹ H-NMR of 400 MHz.

-Bound styrene content (%): Measured by ¹ H-NMR measurement at 400 MHz.

Weight average molecular weight of the polymer before denaturation reaction (peak molecular weight before denaturation reaction): Gel permeation chromatography (GPC) (Viscotek TDA302 (trade name (manufactured by Viscotek)) under the following measurement conditions after the denaturation reaction with a denaturing agent) About the GPC curve obtained by using, it calculated|required by polystyrene conversion from the retention time corresponding to the peak of a peak with the smallest molecular weight.

(GPC measurement conditions)

Column: Trade name "TSK gel HHR-H" (manufactured by Tosoh Corporation) 2

Column temperature: 40°C

Mobile phase: tetrahydrofuran

Flow rate: 1.0 ml/min

Sample concentration: 10mg/20ml

Mooney viscosity (ML ₁₊₄ , 100°C): In accordance with JIS K6300, an L rotor was used to obtain a preheat for 1 minute, a rotor operation time of 4 minutes, and a temperature of 100°C.

[Evaluation of properties of polymer composition (compound rubber)]

Blended Mooney Viscosity: A compounded rubber before vulcanization was used as a measurement sample, and was measured under conditions of preheating 1 minute, rotor operating time 4 minutes, and temperature 100°C using an L rotor in accordance with JIS K6300. It is expressed as an index, and the larger the value, the better the workability.

[Evaluation of properties of vulcanized rubber]

• 0°C tanδ: A vulcanized rubber was used as a measurement sample, and measured under the conditions of 0.1% tensile dynamic strain, 100 radians per second, and 0°C using a dynamic spectrometer (manufactured by Rheometrics, USA). The measurement result is expressed as an index, and the larger the value is, the greater the wet skid resistance is and the better.

-70°C tan δ: A vulcanized rubber was used as a measurement sample, and a dynamic spectrometer (manufactured by Rheometrics, USA) was used to measure a tensile dynamic strain of 0.7%, an angular velocity of 100 radians per second, and 70°C. The measurement result is expressed by an index, and the larger the value, the smaller the rolling resistance and the better the low heat generation property.

<Synthesis and evaluation of modified conjugated diene polymer>

[Example 1: Synthesis of Modified Conjugated Diene Polymer A and Its Physical Properties]

To a nitrogen-substituted 5 liter autoclave reactor, 2,500 g of cyclohexane, 50 g of tetrahydrofuran, 125 g of styrene and 365 g of 1,3-butadiene were added. After the temperature of the contents of the reactor was adjusted to 10°C, 5.20 mmol of n-butyllithium and 4.20 mmol of N-trimethylsilylpiperazine were added as polymerization initiators to initiate polymerization. The polymerization was carried out under adiabatic conditions, and the maximum temperature reached 85°C. When the polymerization conversion rate reached 99% (after 20 minutes from the start of polymerization), 10 g of 1,3-butadiene was added over 2 minutes, and thereafter, 2.60 mmol of a compound represented by the following formula (N-Si-1) And it reacted for 15 minutes.

To the polymer solution containing the obtained modified conjugated diene polymer, 3.96 g of 2,6-di-tert-butyl-p-cresol was added. Subsequently, solvent removal was performed by steam stripping, and a modified conjugated diene-based polymer A was obtained by drying with a hot roll controlled at 110°C. Various physical property values of the obtained modified conjugated diene polymer A are shown in Table 2 below.

[Examples 2 to 5 and Comparative Examples 1 and 2: Synthesis of Modified Conjugated Diene Polymers B to E, P, and Q and Their Physical Properties]

Polymerization was carried out in the same manner as the modified conjugated diene polymer A, except that the type and amount of the polymerization initiator and modifier to be used were as described in Table 1 below, and the solvent was removed from the solution in the same manner as the modified conjugated diene polymer A. By isolating the polymer, modified conjugated diene polymers B to E, P, and Q were obtained, respectively. Various physical property values of the obtained modified conjugated diene polymers B to E, P, and Q are shown in Table 2 below.

In Table 1 and Table 2, the abbreviation of the compound is as follows.

(Polymerization initiator)

*1 INI-1: N-trimethylsilylpiperazine

*2 INI-2: N-(hexyl)piperazine

*3 INI-3: 1,3-ditrimethylsilyl-1,3,5-triazine

*4 INI-4: Piperidine

(Denaturant)

*5 to *8 N-Si-1 to N-Si-4: Compounds represented by each of the following formulas (N-Si-1) to (N-Si-4)

[Production of compounded rubber and vulcanized rubber]

Using the modified conjugated diene polymer prepared above, each component was blended according to the blending formulation shown in Table 3 below, and kneaded to prepare a blended rubber. Kneading was performed by the following method. Using a Plastomill (content: 250 ml) with a temperature control device, first, as the first stage kneading, modified conjugated diene polymer, polybutadiene rubber, extender oil, silica under conditions of 72% filling rate and 60 rpm. , Carbon black, a silane coupling agent, stearic acid, an anti-aging agent, and zinc oxide were mixed and kneaded. Subsequently, as a second-stage kneading, the blend obtained above was cooled to room temperature, and then sulfur and a vulcanization accelerator were blended and kneaded. This was molded and vulcanized at 160° C. for a predetermined time by a vulcanizing press to obtain a crosslinked rubber (vulcanized rubber).

Processability, wet skid resistance, and rolling resistance (low heat generation property) were evaluated by performing compounded Mooney viscosity measurement, 0°C tanδ measurement, and 70°C tanδ measurement using the obtained compounded rubber and vulcanized rubber. The evaluation results are shown in Table 4 below. In addition, the measurement results of the blended Mooney viscosity, 0°C tan δ, and 70°C tan δ were respectively represented by an index using Comparative Example 1 as 100.

In Table 3, about each component, the used brand names are as follows.

*1: BR01 manufactured by JSR, *2: JOMO process NC-140 manufactured by Japan Energy, *3: ZEOSIL 1165 MP manufactured by Rhodia, *4: Diamond Black N339 manufactured by Mitsubishi Chemical, *5: Si75 manufactured by Ebonique , *6: Ozonon 6C manufactured by Seiko Chemical Co., *7: Noxeller D manufactured by Ouchi Shinko Chemical Co., *8: Noxeller CZ manufactured by Ouchi Shinko Chemical Co., Ltd.

All of the modified conjugated diene-based polymers of Examples 1 to 5 have a blended Mooney viscosity higher than that of the modified conjugated diene-based polymer of Comparative Example 1 using piperidine in place of the compound (A), and instead of the compound (A). It was lower than the modified conjugated diene polymer of Comparative Example 2 using piperidine and using the compound (N-Si-4) in place of the compound (M).

In addition, all of the modified conjugated diene-based polymers of Examples 1 to 5 were superior in low heat generation properties and wet grip resistance as compared to the modified conjugated diene-based polymers of Comparative Examples 1 and 2.

From these results, according to the modified conjugated diene polymer obtained by modifying both ends of the conjugated diene polymer using the (A) compound and the (M) compound, the Mooney viscosity of the modified conjugated diene polymer can be appropriately increased, Accordingly, it was confirmed that a vulcanized rubber excellent in low heat generation property and wet grip resistance can be produced while being able to make the compounded rubber excellent in processability.

Claims (7)

A step of polymerizing a monomer containing a conjugated diene compound in the presence of a metal amide compound obtained by mixing an alkali metal compound or an alkaline earth metal compound and the following (A) compound to obtain a conjugated diene-based polymer having an active end;
The step of reacting the conjugated diene-based polymer having the active terminal and a compound represented by the following formula (1)
A method for producing a modified conjugated diene-based polymer comprising a.
(A) a compound having at least one nitrogen-containing group selected from the group consisting of a protected secondary amino group and a tertiary amino group, and one secondary amino group

(In formula (1), R ¹ and R ² are each independently a hydrocarbyl group having 1 to 18 carbon atoms, and R ³ is a hydrocarbylene group having 1 to 20 carbon atoms; R ⁴ and R ⁵ are each independently -NR ^a bond between the carbon-hydrogen atom, hydro-car invoke, or hydro-carbon car of invoking a carbon number of 1 to 18 with the at least one of (where, R is ^a hydro-car pray), -N = and -O- It is a monovalent group having 2 to 18 carbon atoms, or represents a ring structure in which R ⁴ and R ⁵ are combined with each other and constituted with the carbon atom to which they are bonded; provided that R ⁴ and R ⁵ do not simultaneously become a hydrogen atom; n is an integer from 1 to 3; when n is 1, a plurality of R ¹ in the formula is, may be the same or different from each other, n is 2 or 3 when the plurality of R ² in the formula is, may be the same or different from each other good ) The method of claim 1,
The method for producing a modified conjugated diene-based polymer, wherein the compound (A) is at least one selected from the group consisting of a compound represented by the following formula (2) and a compound represented by the following formula (3).

(In formulas (2) and (3), A ¹ , A ² and A ³ are each independently a silyl protecting group or a hydrocarbyl group; R ⁶ , R ⁷ , R ⁸ , R ⁹ and R ¹⁰ are, Each independently a hydrocarbylene group) The method of claim 1,
The method for producing a modified conjugated diene-based polymer, wherein the monomer further contains an aromatic vinyl compound. A modified conjugated diene polymer represented by the following formula (4).

(In formula (4), R ¹ is a C ¹ to C 18 hydrocarbyl group, B ¹ is a C 1 to C 20 hydrocarbyloxy group, or a secondary amino group, a protected secondary amino group and a tertiary amino group A conjugated diene-based polymer chain having at least two or more nitrogen-containing groups selected from the group consisting of; R ³ is a hydrocarbylene group having 1 to 20 carbon atoms; R ⁴ and R ⁵ are each independently hydrogen bond between the carbon -NR ^a - - atom, hydro car invoke, or hydro-carbon car of invoking a carbon number of 1 to 18 (where, R is ^a hydro-car pray), -N = and the carbon atoms having at least one of the 2 -O- It is a monovalent group of -18, or R ⁴ and R ⁵ are combined with each other to represent a ring structure constituted with the carbon atom to which they are bonded; provided that R ⁴ and R ⁵ do not simultaneously become hydrogen atoms; Poly is 2 A conjugated diene-based polymer chain having at least two at the end of at least one nitrogen-containing group selected from the group consisting of a secondary amino group, a protected secondary amino group and a tertiary amino group; n is an integer of 1 to 3; n is 1 In the case of, a plurality of R ¹ in the formula may be the same or different from each other, and when n is 2 or 3, a plurality of B ¹ in the formula may be the same or different from each other.) A polymer composition comprising a modified conjugated diene polymer obtained by the production method according to any one of claims 1 to 3 or a modified conjugated diene polymer according to claim 4, silica, and a crosslinking agent. A crosslinked product obtained by crosslinking the polymer composition according to claim 5. A tire in which one or both of a tread and a side wall are formed using the polymer composition according to claim 5.